Generally, valve devices are used for regulating the flow of a fluid (e.g. gas or liquid) by opening, closing, or partially obstructing various passageways. Valve devices are widely found in household applications, industrial applications or other applications. For example, faucets and waterway gate valves are found in regular applications. In addition, check valves, regulating valves or water control valves are widely used in industrial applications.
As known, a water solenoid valve is one of the most common valve devices. FIG. 1A is a schematic view illustrating a normally-closed water solenoid valve according to the prior art. The water solenoid valve 1 includes a valve body 11, a rubber pad 12 and a solenoid valve 13. The valve body 11 includes an inlet port 111 and an outlet port 112. The solenoid valve 13 includes a solenoid coil 131, a plunger 132 and a spring 133. The plunger 132 is axially movable with respect to the solenoid coil 131. The rubber pad 12 is installed within the valve body 11. The valve body 11 is connected with the solenoid valve 13. The rubber pad 12 is in an annular structure and arranged between the valve body 11 and the solenoid valve 13 for preventing leakage of the water.
Normally, water is introduced into a fluid receptacle 113 between the rubber pad 12 and the solenoid coil 131 through the inlet port 111 and the perforations 121 of the rubber pad 12. When an electric current flows through the solenoid coil 131, a magnetic field is created by the solenoid coil 131. The magnetic field causes the plunger 132 to be internally drawn back with respect to the solenoid coil 131. As the plunger 132 is internally drawn back, the water stored in the fluid receptacle 113 is outputted through the rubber pad 12 and the outlet port 112 (see FIG. 1B). Whereas, when the electric current is stopped, the plunger 132 is pushed out with respect to the solenoid coil 131 in response to a restoring force of the spring 133. As the plunger 132 is pushed out, the rubber pad 12 is sealed by the plunger 132. Under this circumstance, the fluid receptacle 113 is not in communication with the outlet port 112, and thus the water is stored in the fluid receptacle 113 and fails to be outputted.
Although the water solenoid valve 1 is effectively to regulate the flow of a fluid, there are still some drawbacks. For example, since the metallic components (e.g. the plunger 132 and the spring 133) are immersed in the water, the metallic components are readily corroded to result in breakdown of the water solenoid valve 1. In addition, the water temperature and the residual chemical substance of the water may gradually degrade the rubber pad 12. Since the rubber pad 12 is very thin, the impact of intermittent pressure may deform the rubber pad 12. Under this circumstance, the rubber pad 12 is damaged and thus the water solenoid valve 1 is failed. Moreover, as the pressure of the water flowing through the water solenoid valve 1 is increased, the power consumption is increased.
That is, the drawbacks of the conventional water solenoid valve include immersion of some metallic components (e.g. the plunger and the spring) in water, degradation of the rubber pad by the water temperature and the residual chemical substance of the water, deformation resulting from the impact of intermittent pressure, and high power consumption for driving the plunger.